# CVE-2026-117883: firefox-esr: Use-after-free in the DOM: HTML Parser component

CVE-2026-117883 is fixed in 4 products on 1 platform, first by DEBIAN-CVE-2026-117883, released October 29, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-117883
- Priority: High
- CVSS: 8.8 (high)
- EPSS: 0.0040
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Oct 27, 2026

## Description

Use-after-free in the DOM: HTML Parser component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | firefox ol 10 | 0:153.6.0-1.0.1.el10_2 | [ELSA-2026-93956](https://patchblox.com/security/data/fix/linux/elsa-2026-93956.md) | Nov 7, 2026 |
| Linux | firefox ol 8 | 0:153.6.0-1.0.1.el8_10 | [ELSA-2026-94405](https://patchblox.com/security/data/fix/linux/elsa-2026-94405.md) | Nov 7, 2026 |
| Linux | firefox ol 9 | 0:153.6.0-1.0.1.el9_8 | [ELSA-2026-93957](https://patchblox.com/security/data/fix/linux/elsa-2026-93957.md) | Nov 7, 2026 |
| Linux | firefox-esr Debian 12.15 (bookworm) | 153.6.0esr-1~deb12u2 | [DEBIAN-CVE-2026-117883](https://patchblox.com/security/data/fix/linux/debian-cve-2026-117883.md) | Oct 29, 2026 |
| Linux | firefox-esr Debian 13.5 (trixie) | 153.6.0esr-1~deb13u1 | [DEBIAN-CVE-2026-117883](https://patchblox.com/security/data/fix/linux/debian-cve-2026-117883.md) | Oct 29, 2026 |
| Linux | firefox-x11 ol 9 | 0:153.6.0-1.0.1.el9_8 | [ELSA-2026-93957](https://patchblox.com/security/data/fix/linux/elsa-2026-93957.md) | Nov 7, 2026 |
| Linux | thunderbird Debian 12.15 (bookworm) | 1:153.6.0esr-1~deb12u2 | [DEBIAN-CVE-2026-117883](https://patchblox.com/security/data/fix/linux/debian-cve-2026-117883.md) | Oct 29, 2026 |
| Linux | thunderbird Debian 13.5 (trixie) | 1:153.6.0esr-1~deb13u1 | [DEBIAN-CVE-2026-117883](https://patchblox.com/security/data/fix/linux/debian-cve-2026-117883.md) | Oct 29, 2026 |

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Data as of 2026-11-08T19:12:23Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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